1. Field of the Invention
The present invention generally relates to producing imitation- and duplication-resistant objects such as smart cards, and more particularly to producing hard to copy and hard-to-imitate identifying marks on objects, as well as hard-to-copy and hard-to-imitate objects such as smart cards, and to problems relating to the reader needed to utilize such cards.
Further, the present invention also relates to preventing adversaries from modifying the data and program content of such cards.
2. Description of the Related Art
One of a kind samples: The use of radio frequency automatic identification systems has been proposed as a general purpose authentication system in U.S. Pat. No. 5,581,257 by Morton Greene et al.
This system offers high security, and has been proposed for the protection of identification documents, credit cards, and money. In this system, processes generate one of a kind (e.g., unique), non-duplicable, samples of certain encapsulated metal fibers, randomly placed, so that the samples can be identified by some reading mechanism. For example, a mechanism may be employed which uses microwaves as an interrogating source. The tag contains hundreds of small metal fibers of random orientation and lengths encapsulated in a medium such as, for example, paper or plastic.
The chances of there being two tags having a same configuration that would give the same microwave signature upon interrogation are extremely improbable and are essentially zero. The reader can be part of the computer which verifies the rightful use of the computer by a potential user. If the signature read by the microwave reader is one that does not conform to the original reading of the card stored in the computer memory, or more generally in some database accessible by the computer, access to the computer will be denied.
An inhomogeneous media has been proposed in U.S. Pat. No. 5,790,025 as another example of an arbitrarily or randomly arranged medium which is interrogated by a coherent light beam by way of the detected optical scattering from the material. Its main purpose is to detect intrusion into a protected area. Thus, if one tries to change the medium in any way, the original pattern of the scattered coherent light will be changed and in the present application, the computer will not operate.
Here, reading is accomplished using the light beam from a solid state laser diode in combination with a small scanning mirror and optical detector, all of which may be an integral part of the computer. If the randomly arranged medium on the card has been altered for an attempted illegal intrusion, the pattern stored in the computer memory will not match the pattern scanned and the computer will not operate.
Other examples of samples for which only one of a kind exist are given by glasses and crystallites which can have a uniquely random set of defects or features. These features result in a unique configuration of colors and/or fractures which gives a complicated, irreproducible stable pattern once cooled. Cooling generally occurs because many of these configurations are formed at high temperatures and subsequently in many cases quenched, thereby giving these unique patterns in the form of dislocations, cracks, grain boundaries and colors, as described above. Rocks such as shale, marble, granite, sandstone, and limestone can also have unique features.
Any of the materials discussed herein having considerable hardness can be made scratch- and tamper-resistant by covering the sample with thin layers of diamond-like carbon, using techniques well known in material sciences, and commercially provided by various companies such as General Vacuum Inc. of Cleveland, Ohio.
Smart cards: Smart cards have been proposed as a technology offering the possibility of secure off-line transactions. However, recently, several successful attacks on conventional smart cards have been reported (see, for example, R. Anderson, M. Kuhn; “Tamper Resistance—A Cautionary Note.” The Second USENIX Workshop on Electronic Commerce, November 1996, R. Anderson, M. Kuhn; “Low Cost Attacks on Tamper Resistant Devices.” Preprint. 1997, and P. Kocher, J. Jaffe and B. Jun, “Introduction to Differential Power Analysis and Related Attacks” Manuscript, Cryptography Research, Inc. 1998). One such reported attack allows cracking of the digital code which is supposed to warranty the security of the card, by inferring conclusions of the code from observations of electrical currents, power consumption, and other electromagnetic manifestations in the card during use. Other low-cost attacks are similarly known on current smart card technology.
Given the benefits that banks, credit card companies, and other users were expecting from a wide acceptance of the security offered by smart cards, it is important to be able to overcome the lack of security offered by present day smart card technology.
Indeed, several improvements of the original design have been proposed (and this process may continue in the future). However, since the above-described, successfully mounted attack only needs some of the electrical analysis and possibly the physical attacks one could perform on smart cards, the desired level of confidence will likely not be restored so long as solutions only push further the original (and conventional) idea of enclosing all the security in the card.